Field
Embodiments described herein relate generally to a semiconductor memory device and a manufacturing method thereof.
Description of the Related Art
A semiconductor memory device such as a NAND flash memory is required to be further downsized and has a larger storage capacity. While scaling down for enhancing the capacity has been done, on the other hand, there has been proposed a structure in which semiconductor elements such as memory cells are disposed three-dimensionally. For example, in such three-dimensional semiconductor memory device, the memory cells are disposed in a laminating direction. Conductive layers extend from the respective memory cells, which are disposed in the laminating direction.
In such three-dimensional semiconductor memory device, the laminated conductive layers are connected to contacts on their top surfaces. As the miniaturization has been developed, the reduction in contact diameter is desired. However, the small contact diameter increases a contact resistance between the contact and the conductive layer.